This proposal is for the purchase of a Bio-Rad MicroRadiance confocal laser scanning microscope system including a Nikon Eclipse TE300 inverted microscope as a multi-user shared instrument. The confocal microscope will be located in and maintained by the Institute for Environmental Medicine under the supervision of the PI. Operational and maintenance costs will be recovered from an annual contribution from the users, and technical support will be provided from the Institute's operational budget. The common scientific thread in the research measures, and treatment of acute lung diseases in the newborn and the adult. The projects involve study of generation of tissue- damaging oxidants and their regulation, cell adhesion molecule function, genetic and pathophysiologic regulation of surfactant proteins and lipids, signal transduction and cell-cell communication. The projects will use isolated rat and mouse lungs, cultured type II and smooth muscle cells from rat lungs and other available lung cell lines, human fetal lung explants, leukocytes and rat brain blood vessels. These studies, often in live cells, thick explant tissue, or isolated lung, require confocal microscopic techniques using fluorescence probes for visualization of cell biological processes. The investigators participating in this proposal carry out research requiring cytological localization and quantification of molecules pertinent to their fields of study, namely: surfactant phospholipid trafficking (Shuman), assessment of endothelial dysfunction in lung ischemic injury (Fisher), evaluation of cellular distribution and function of PECAM-1 (Albelda), determination of the cellular and subcellular sites of surfactant protein SP-C processing (Beers), study of distribution of ICAM and nitrotyrosine in CO-poisoning (Thom), assess distribution of C/EBP and proSP-C (Feinstein), study of trafficking of SP-B intermediates and GPF (Guttentag), evaluation of cytoskeletal and signal transduction proteins in tracheal smooth muscle cells (Coburn), study of cellular distribution of PECAM-1, GOX and catalase (Muzykantov), and determination of colocalization and trafficking of gap junction proteins connexins 43 and 26 (Koval). These projects which are currently supported by 3,172,240 dollars per annum in total costs from NIH will be greatly facilitated by the greater availability of a confocal microscope.